Field of the Invention
The invention relates to a proximity sensor and particularly to a proximity sensor using the antenna structure as a sensing conductor and a mobile communication device thereof.
Description of Related Art
Mobile communication devices, such as mobile phones, personal digital assistants (PDAs) and tablets have become extremely popular and for many users are considered indispensable.
One of the most important components of mobile communication devices are their antennas, which are configured to radiate and receive electromagnetic waves so as to transmit and exchange wireless information between the mobile communication device and other devices.
Generally speaking, electromagnetic waves radiated by an antenna may often be harmful to human health, so that the Federal Communications Commission (FCC) specifies a specific absorption ratio (SAR) for electronic apparatus to limit radiation energy of the electronic apparatus or to define a maximum radiation limit for the electronic apparatus.
In order to make the SAR value to comply with a test specification, in the conventional electronic apparatus, sensing antennas are configured to both ends of a communication antenna, and sensors are used in collaboration with the sensing antennas to detect a distance between the electronic apparatus and human body, so as to determine whether or not to decrease a radiation power of the communication antenna, and maintain the SAR value within a safe test range.